1. Field of the Invention
The present invention provides a deformable high pressure seal assembly which allows for selective bleeding of pressure fluid in one direction, and seals against high pressure in the other direction.
2. Prior Art
Seal ring assemblies are typically used to prevent high pressure fluid from traveling across an annular channel or opening. Such seals may be subjected to pressures up to 20,000 pounds per square inch from either axial direction. Such operating conditions have caused problems due to the seals extruding through the channel or opening.
A seal assembly is disclosed in U.S. Pat. No. 3,394,941 wherein the seal ring assembly opposes fluid pressure in a forward axial direction. This seal ring assembly includes an elastomeric ring, a first nonelastomeric ring engageable with the elastomeric ring, and a second nonelastomeric ring configured to prevent harmful extrusion of the elastomeric ring when acting as a sealing surface against the high pressure fluid. The nonelastomeric rings are preferably fabricated from a fluorocarbon and reinforced with embedded fibers.
U.S. Pat. No. 3,885,801 discloses a ring assembly for sealing in two directions. The ring assembly comprises an elastomeric seal ring with a pair of lips, and a solid elastomeric loading ring disposed between the lips. A pressure inverting pedestal ring is also used in the assembly and is active on the loading ring such that when the fluid pressure is behind the pedestal ring, the fluid pressure bypasses the pedestal ring and acts upon the loading ring to deform the same to press the lips into sealing engagement. When fluid pressure originates from the opposite direction, the seal ring and loading ring are brought into sealing engagement with the pedestal ring.
U.S. Pat. No. 4,013,299 is directed to yet another configuration for a seal ring. In this patent, the seal ring provides for sealing in one axial direction. The sealing ring comprises a U-shaped cup having a pair of lips for forming a cavity therebetween, and an elastomeric expander ring mounted within the cavity. Sealing edges on the lips are contacted by members to be sealed and are positioned on the outside of the lips at a vertical location at or below the horizontal center line of an expander ring when the expander ring is mounted within the cavity. This particular orientation of the sealing edges reduces the rotation of the inner top lip portions into the expander ring, thereby keeping the sealing edges in contact with the members to be sealed.
Other similar sealing assemblies are disclosed in U.S. Pat. No. 3,603,603 to Woodson, and U.S. Pat. No. 3,109,661 to Swain et al.
The inventions described in these prior art references all relate to a sealing assembly designed to oppose high fluid pressure across the seal in either one or two directions. The references are uniform in their reliance on an elastomeric loading or expander ring disposed within retaining lips. The ring expands or contracts under the force exerted by the retaining lips.
It is a primary objective of the present invention herein disclosed to provide a means for selective bleeding of pressure fluid such that when the fluid is exerted in one direction, the assembly provides an effective high pressure seal. When the fluid is exerted in the opposite direction, the assembly allows for bleeding of the fluid across the seal, relieving the pressure.
It is another objective of this invention to provide a seal assembly which includes a nonelastomeric loading or spacer ring which is not susceptible to fatigue or distortion.
It is a further objective of this invention to provide a seal assembly which includes a metal back-up ring positioned against a point of fluid departure, which can provide an effective sealing surface for pressures of up to 20,000 pounds per square inch without being extruded through the point of fluid departure.